We propose to develop a new objective method for gross selection of patients who are candidates for surgical portalsystemic decompression because of cirrhosis of the liver with associated portal hypertension. The selection will be aimed to identify two main categories of patients: those who may not survive the immediate insult of the operation and those, who surviving the surgical procedure, may become crippled by severe forms of portalsystemic encephalopathy. On the basis of our previous studies, we propose that a useful criterion for selection should be the ability of the hepatic arterial bed to adjust its arteriolar resistance in response to the downstream lowering in sinuosoidal pressure effected by the portacaval shunt. In our studies, the ability revealed itself by the extent of the increase in hepatic arterial flow directly measured in our patients before and after construction of the shunt. We further propose that this ability should be a function of the degree of entrapment of the arterioles by the fibrous tissues of cirrhosis. Should our working hypothesis prove correct, there should be a direct correlation between the post-shunt ability to increase arterial flow and the elastic properties of the hepatic arterial bed in cirrhosis. We intend to quantify these elastic properties by measuring the characteristic input impedance of the hepatic arterial bed in cirrhosis and, thus, to advance toward our long range goal of identifying patients that may not survive the operation or may develop severe forms of encephalopathy.